In a wireless communication system, the constellation mapping scheme employed may be changed on a per-time-slot basis, i.e., from time slot to time slot, so that the constellation used to encode the symbols of each time slot may be different for each time slot within a single frame and may be different for a particular time slot in different consecutive frames. In other words, several constellation mapping schemes are available, with each providing the ability to transmit a different number of bits per symbol, and the particular constellation mapping scheme employed for any time slot need be selected for that time slot only. The ability to use any particular constellation mapping scheme is dependent on the current channel quality. The particular constellation mapping used for the user data of the time slot may be indicated in the preamble of the time slot. To this end, each time slot may have its own preamble that is mapped with a constellation mapping scheme which is a) known à priori, b) may be the same for all time slots, and c) may be different from the constellation mapping scheme used to encode user data in the time slot. A receiver can determine the constellation mapping used for each time slot from solely from the preamble of the time slot.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for determining a modulation scheme used in mapping of a user's data on a per-time-slot basis, the method comprising the steps of: performing at least one correlation of a portion of said time slot and at least two known training sequences that are each indicative of a particular one of a plurality of modulations schemes that are permitted to have been employed to modulate said user's data; and selecting a modulation scheme that corresponds to the at least one known training sequence that produces the best correlation result in said performing step.
2. A method for use in a receiver that is adapted to receive a transmission modulated using, on a per-time-slot basis one of a plurality of multiple constellation mapping schemes, each said time slot having a preamble, said method comprising the steps of: correlating N 1 symbols, which are in positions in said preamble at which a training sequence is expected, with each of a plurality of first known training sequences; using a constellation mapping scheme that corresponds to a first one of said first plurality of known training sequences when a first one of said plurality of known training sequences is most highly correlated with said first N 1 symbols; correlating N 2 symbols of said preamble with each of a plurality of known second training sequences, each of said second training sequences corresponding to a respective one of said constellation mapping schemes other than the one of said constellation mapping schemes corresponding to said first one of said plurality of known training sequence; using the constellation mapping scheme that corresponds to a one of said second plurality of known training sequences that is the most highly correlated with said N 2 symbols when said first one of said plurality of known training sequences is not most highly correlated with said first N 1 symbols and performing training of said receiver using said at least N 1 symbols when said first one of said plurality of known training sequences is the most highly correlated with said first N 1 symbols and using at least said at least N 2 symbols when said first one of said plurality of known training sequences is not the most highly correlated with said first N 1 symbols.
3. The invention as defined in claim 2 further wherein said N 2 symbols are distinct from said N 1 symbols.
4. The invention as defined in claim 2 wherein the step of performing training of said receiver uses at least said N 1 and said at least N 2 symbols when said first one of said plurality of known training sequences is not the most highly correlated with said first N 1 symbols.
5. Apparatus for use in a receiver that receives a transmission modulated using, on a per-time-slot basis one of a plurality of multiple constellation mapping schemes, each said time slot having a preamble, said apparatus: means for correlating N 1 symbols, which are in positions in said preamble at which a training sequence is expected, with each of a plurality of first known training sequences; means for using a constellation mapping scheme that corresponds to a first one of said first plurality of known training sequences when a first one of said plurality of known training sequences is most highly correlated with said first N 1 symbols; means for correlating N 2 symbols of said preamble with each of a plurality of known second training sequences, each of said second training sequences corresponding to a respective one of said constellation mapping schemes other than the one of said constellation mapping schemes corresponding to said first one of said plurality of known training sequence; means for using the constellation mapping scheme that corresponds to a one of said second plurality of known training sequences that is the most highly correlated with said N 2 symbols when said first one of said plurality of known training sequences is not most highly correlated with said first N 1 symbols; and means for performing training of said receiver using said at least N 1 symbols when said first one of said plurality of known training sequences is the most highly correlated with said first N 1 symbols and using at least said at least N 2 symbols when said first one of said plurality of known training sequences is not the most highly correlated with said first N 1 symbols.
6. The apparatus as defined in claim 5 further wherein said N 2 symbols are distinct from said N 1 symbols.
7. The apparatus as defined in claim 5 further including means for using at least said N 1 along with said at least N 2 symbols when said first one of said plurality of known training sequences is not the most highly correlated with said first N 1 symbols.
8. A method for use in a receiver comprising the step of receiving a transmission that is modulated using, on a per-time-slot basis, one of a plurality of multiple constellation mapping schemes, each said time slot having a preamble; said method being further CHARACTERIZED by the steps of correlating a first portion a preamble of a particular time slot with each of a first plurality of known training sequences; using a constellation mapping scheme that corresponds to a first one of said first plurality of known training sequences when said first one of said first plurality of known training sequences is the most highly correlated with said portion of said preamble as the particular one of said plurality of multiple constellation mapping schemes is being used for said particular time slot; training said receiver at least as a function of said first one of said first plurality of known training sequences, when said first one of said first plurality of known training sequence is the most highly correlated with said portion of said preamble as the result of said determining step; correlating, when said first one of said first plurality of known training sequences is not the most highly correlated with said first portion of said preamble, a second portion of said preamble with each of a plurality of second known second training sequences, each of said second known training sequences corresponding to a respective one of said constellation mapping schemes other than the one of said constellation mapping schemes corresponding to said first one of said first plurality of known training sequences; using, when said first one of said first plurality of known training sequence is not the most highly correlated with said first portion of said preamble, a constellation mapping scheme that corresponds to a one of said second plurality of known training sequences that is the most highly correlated with said second portion of said preamble; and training said receiver at least as a function of said one of said second plurality of known training sequences that is the most highly correlated with said second portion of said preamble when said first one of said first plurality of known training sequence is not the most highly correlated with said first portion of said preamble.
9. The method as defined in claim 8 being further CHARACTERIZED in that said training in said step of training said receiver at least as a function of said one of said second plurality of known training sequences that is the most highly correlated with said second portion of said preamble is performed such that it is also at least a function a training sequence of said first plurality of known training sequences other than said first one of said first plurality of known training sequences when said first one of said first plurality of known training sequence is not the most highly correlated with said first portion of said preamble.
10. Software in a computer readable form for determining a modulation scheme used in mapping of a user's data on a per-time-slot basis, the software being CHARACTERIZED by: a module for performing at least one correlation of a portion of said time slot and at least two known training sequences that are each indicative of a particular one of a plurality of modulations schemes that are permitted to have been employed to modulate said user's data; and a module for selecting a modulation scheme that corresponds to the at least one known training sequence that produces the best correlation result by said means for performing.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 27, 1999
August 24, 2004
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